Imported from yves-chevallier/texsmith (.claude/skills/writing-texsmith/SKILL.md). Install upstream with npx skills add yves-chevallier/texsmith --skill writing-texsmith. Copyright stays with the author.

Writing documents for TeXSmith

TeXSmith converts Markdown into LaTeX (default) or Typst, then optionally compiles a PDF. You author plain Markdown enriched with a few PyMdown extensions and a handful of TeXSmith-specific conventions. This skill is the reference for producing .md sources that render cleanly on the first build.

Golden rule — separate content from form. Everything about appearance (template, paper size, fonts, margins, callout style, title, authors) lives in the YAML front matter. The body carries only ideas, prose, and equations. Never hardcode LaTeX styling in the body unless there is no Markdown equivalent.

Build command (for reference — you author the .md, the user builds):

texsmith document.md -o build/ --build            # LaTeX → PDF (Tectonic)
texsmith document.md references.bib -t book -o build/ --build
texsmith document.md --format typst -o build/ --build

1. YAML front matter (mandatory scaffolding)

A document opens with a YAML island fenced by --- at the very top of the file (line 1). Put typographic config under a press: block; title/authors/date may sit either under press: or at the root.

---
title: Albert Einstein
subtitle: His Life and Achievements
authors:
  - name: Ada Lovelace
    affiliation: Analytical Engine
  - name: Grace Hopper
date: 2025-03-15        # ISO date, or "commit" for last git commit date
press:
  template: book        # article (default) | book | letter
  paper: a4             # a4 | a5 | letter …
  base_level: chapter   # part | chapter | section — what the top `#` maps to
  fonts: adventor
  callout_style: fancy  # fancy (default) | classic | minimal
  slots:
    abstract: Abstract    # map a "## Abstract" section into the template's slot
    preface: Preface
---

Key fields:

template : article (default), book, or letter. Pick book for long multi-chapter documents, letter for correspondence (see §11), article otherwise.

title : If omitted, TeXSmith promotes the document's first heading to the title. Set title: null to render with no title while keeping the first heading as content.

authors : A string, a list of strings, or a list of {name, affiliation} objects. name is required; a missing name is a hard error.

date : ISO date (2024-07-01), a string, a {year, month, day} map, or the special commit (date of last git commit). Formatted per template locale at render time.

base_level : What the top-level # heading becomes. chapter (books), section (articles). Equivalent to the CLI --base-level.

slots : Map a document section (by heading text) into a named template slot (abstract, preface, dedication, colophon…). Inspect a template's slots with texsmith -t <template> --template-info before wiring them.

Inline bibliography and glossary also live in front matter — see §9 and §10.

2. Document structure & page breaks

Headings use standard #…######. Numbering and the mapping to LaTeX sectioning is driven by base_level, so do not manually number headings.

Page break = a horizontal rule. A line containing only --- (with a blank line before and after) renders as \clearpage in LaTeX. This is the only way to force a page break from Markdown.

Last paragraph of the current page.

---

First paragraph of the next page.

⚠️ Gotcha: because --- is a page break, never use it as a decorative section separator. The --- at the very top of the file is the front-matter fence, not a rule. To break inline instead of using a rule, drop {latex}[\clearpage] into a paragraph.

3. Text formatting

*italic*   **bold**   ***bold italic***   ~~strikethrough~~   `inline code`
__small capitals__

⚠️ Gotcha: __double underscores__ render as small capitals, not bold. Use ** for bold. A standalone paragraph made of a single short bold span (< 80 chars) is promoted to a lead-in pseudo-heading (\tslead), handy for labelling.

4. Lists

- Unordered
  - Nested
1. Ordered
2. Next

- [x] Completed task
- [ ] Pending task

5. Definition lists

A term on its own line, then one or more definitions each introduced by : followed by at least one space (align continuation lines under the text). Leave a blank line between entries.

Apple
:   Pomaceous fruit of plants of the genus Malus in
    the family Rosaceae.

Orange
:   The fruit of an evergreen tree of the genus Citrus.

Renders as a LaTeX description environment. Great for glossaries of terms, option references, and parameter documentation.

6. Admonitions (callouts)

!!! note "Optional title"
    Indented body — any Markdown, multiple paragraphs allowed.

??? tip "Collapsible"
    Use `???` for a foldable callout, `???+` for one open by default.

Built-in types: note, tip, warning, important, danger, info, hint, seealso, question, abstract. Rendered as tcolorbox blocks; style is set globally via callout_style in front matter (fancy | classic | minimal).

7. Figures, images & captions

Basic image with optional width (percentage or absolute length):

![Alt text](assets/photo.jpg){width=60%}

To make it a numbered, cross-referenceable figure, follow the image with a /// caption block. Attach an id with attrs: {id: fig:my-figure} — always prefix figure ids with fig:.

![Short caption for the list of figures](assets/photo.jpg){width=60%}

/// caption
    attrs: {id: fig:my-figure}
This is the full caption shown under the figure.
///

• The image alt text is reused as the short caption in the List of Figures.
• Reference it with the @[label] shorthand or an empty-text link to #fig:…:

As shown in Figure @[fig:my-figure], the result is clear.
As shown in Figure @fig:my-figure, brackets are optional for one-word labels.
As seen in [](#fig:my-figure), the result is clear.

Any link whose fragment starts with fig: (or tab:, sec:, eq:, code:) is auto-decorated with its number and the locale-correct label word ("Figure"/"figure"/ "Abbildung"…). Never hardcode "Figure 3" — let numbering resolve it, and avoid the words "above"/"below" (floats move in print).

8. Tables

Simple pipe tables

Table: Caption for the table. {#tbl:stock}

| Option        | Description                     |
| ------------- | ------------------------------- |
| `--build`     | Compile the PDF after rendering |
| `--debug`     | Show full tracebacks            |

The Table: … {#tbl:label} line directly before the table sets its caption and label. Reference with Table @[tbl:stock].

Add layout metadata to a pipe table with a yaml table-config fence immediately after it (positional column specs — no spans/footers):

| Abbr. | Course        | Load |
| ----- | ------------- | ---- |
| Info1 | Informatique  | 120  |

```yaml table-config
columns:
  - {align: left}
  - {align: justify, width: X}   # X = flexible column that wraps
  - {align: right}
```

Rich tables (spans, grouped headers, footers)

Use a yaml table fence when you need grouped headers, row/column spans, separators, or footers. It is validated before rendering, so typos fail locally instead of producing a broken PDF.

Table: Quarterly sales {#tbl:sales}

```yaml table
table:
  width: 100%
columns:
  - Product
  - name: FY24
    columns: [Q1, Q2, Q3, Q4]
    width-group: quarter
rows:
  - [Apples, [120, 135, 150, 140]]
  - separator: {label: Seasonal}
  - [Cherries, {value: "n/a", cols: 4, align: c}]
footer:
  - [Total, [—, —, —, —]]
```

Rules to remember: ~ is an empty cell and the "absorbed by a span" marker (every slot a span covers must be ~); the first column is the row-label column; quote cell values that contain Markdown/YAML punctuation. See the table docs for the full schema.

9. Math

Uses LaTeX/MathJax syntax. Inline with $…$ or \(…\); display with $$…$$.

Inline: $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$.

$$
\imath \hbar \frac{\partial}{\partial t} \Psi(\mathbf{r},t) =
\left[ -\frac{\hbar^2}{2m} \nabla^2 + V(\mathbf{r},t) \right] \Psi(\mathbf{r},t)
$$

⚠️ Gotcha: no space right after the opening $ or \( — $ x$ breaks the parser.

Numbered / referenceable equations use \label{} inside an equation/align environment (wrapped in $$), referenced with $\eqref{…}$ or the @[label] shorthand:

$$
\begin{equation} \label{eq:einstein}
E = mc^2
\end{equation}
$$

As shown in Equation @[eq:einstein], energy equals mass times $c^2$.

10. Code blocks

Fenced blocks with a language and optional attributes:

```python title="bubble_sort.py" linenums="1" hl_lines="2-3"
def bubble_sort(items):
    for i in range(len(items)):
        ...
```

Options: title="…", linenums="1", hl_lines="2-3". Highlighted with Pygments by default (press.code.engine also accepts listings, verbatim, minted). Inline highlighted code: `#!py print("hi")`. To make a listing referenceable, wrap it in a !!! listing {#code:label} admonition and reference it with Listing @[code:label].

Long inline code overflowing the margin? Let it wrap on identifier separators, and optionally drop its colouring, with press.code.inline: {breaks: "_./", plain: true}.

11. Cross-references & links

Footnotes are limited to one line in print — keep them tight. Citations reuse footnote syntax with a bibliography key: Einstein's work.[^einstein1905] where the key is defined in front matter or a .bib file.

12. References & glossary in front matter

Bibliography — inline entries or DOI shortcuts (a .bib file also works):

bibliography:
  einstein1905: https://doi.org/10.1002/andp.19053221004
  CD2019:
    type: book
    author: "John Doe"
    title: "Example Book"
    year: "2019"

Glossary (when the feature is enabled):

glossary:
  style: long          # long | short
  groups:
    symbols: Mathematical symbols
  entries:
    "$\\phi$":
      group: symbols
      description: Angle in radians
    AI:
      description: Artificial Intelligence

13. Escaping to raw LaTeX

Only when Markdown has no equivalent. Block form:

/// latex
\begin{align}
E &= mc^2 \\
\nabla \cdot \vec{E} &= \frac{\rho}{\varepsilon_0}
\end{align}
///

Inline form inside a paragraph: The section ends here {latex}[\clearpage] before the appendix.

14. The letter template

For correspondence, the whole structure lives in front matter; the body is the letter text and the first heading is the salutation.

---
press:
  template: letter
  date: 1903-07-14
  signature: signature.svg
  from:
    name: Marie Skłodowska Curie
    address: |
      Laboratory of Physics and Chemistry
      Sorbonne University, Paris
  to:
    name: Leonardo da Vinci
    address: |
      Casa di Leonardo
      Florence
  ps: |
    A postscript line.
---
# Dear Maestro Leonardo

Body of the letter…

Pre-flight checklist (avoid failed builds)

Before handing off a TeXSmith document, verify:

• Front matter is at line 1, fenced by ---, valid YAML, with a template.
• Headings are not manually numbered; base_level matches the template.
• --- is used only for intentional page breaks (blank line before/after).
• Bold is **…**; __…__ was used only where small caps are actually wanted.
• No space after $/\( in math; every \label referenced with @[…]/\eqref.
• Figures use ![alt](src){width=…} + /// caption with an id: fig:….
• Cross-references use @[label] / empty-text links — no hardcoded numbers or "above"/"below".
• Tables needing spans/grouped headers use yaml table; span slots are ~.
• Every citation key ([^key]) exists in bibliography front matter or a .bib.
• Raw LaTeX confined to /// latex … /// or {latex}[…].